GROWTH CONE ADVANCE: AN IMMUNOCHEMICAL AND ULTRASTRUCTURAL STUDY OF ACTIN, MYOSIN, TROPOMYOSIN, AND FIBRONECTIN IN NEUROBLASTOMA CELLS.
Item
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Title
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GROWTH CONE ADVANCE: AN IMMUNOCHEMICAL AND ULTRASTRUCTURAL STUDY OF ACTIN, MYOSIN, TROPOMYOSIN, AND FIBRONECTIN IN NEUROBLASTOMA CELLS.
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Identifier
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AAI8713780
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identifier
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8713780
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Creator
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MUIR, DAVID FULTON.
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Contributor
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Soli Berl
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Date
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1987
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Neuroscience
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Abstract
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The constitutive neurite-producing human neuroblastoma (Nb) cell line SH-SY5Y was used as a model for developing autonomic neurons in vitro. Neuronal and non-neuronal characteristics of these cells were observed and aspects of cellular differentiation were examined in response to morphology-altering agents, particularly the tumor promoter 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA). SH-SY5Y Nb cells extended neurites with growing tips which had arrays of filament bundles that coursed into filopodial protrusions. These structures were examined in detail in growth cones prepared as whole mounts for light and transmission electron microscopy and immunolabeled using specific antibodies against actin, myosin, tropomyosin and fibronectin (FN). The potential role of these proteins in the process of filopodia-mediated growth cone advance was elucidated by the localization of actin and myosin to filopodia and filament bundles associated with sites of substratum attachment containing FN.;SH-SY5Y Nb cells secreted FN into defined medium and formed substratum-attachment sites that contained FN. Cells immunolabeled for FN with colloidal gold probes demonstrated densely labeled substratum-attachment plaques on filopodia (contact pads) and on the underside of distal growth cones (focal plaques) that appeared in close association with microfilament bundles coursing into filopodia. Immunolabeling live cells with a pulse of anti-FN antibody provided evidence that filopodial contact pads may be the precursor form of focal attachment plaques later to be found under the body of the advancing growth cone. Both sites were more abundant on the distal tips of cells grown in defined medium supplemented with serum FN and correlated with neurite production.;Under the same conditions, neurite sprouting (in serum-free medium) was substantially retarded in the presence of PMA; the alteration in neurite elongation was partially antagonized by the addition of FN to the medium or substratum. PMA-treated SH-SY5Y cells produced neurites with growth cones lacking filopodia and microfilament bundles. Actin filaments were rearranged into a dense meshwork and the association with myosin and tropomyosin was diffuse. In addition, FN-containing sites were scant and greatly diminished in FN-immunolabel. Substratum-attachment plaques were not evident on PMA-induced growth cones nor were arrays of cytoskeletal filament bundles.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Biomedical Sciences
